Stainless Steel (SS) Pipe Dimensions Chart

Stainless Steel (SS) Pipes are essential in industries requiring corrosion resistance, hygiene, and durability—such as chemical processing, food and beverage, pharmaceuticals, and oil and gas. Selecting the correct pipe size, schedule, and weight is critical for system performance, safety, and cost control.

This article provides a complete reference for stainless steel pipe dimensions, covering seamless and welded pipe types, in both metric (mm) and imperial (inch) units. All dimensional data follows ASME/ANSI B36.19, the standard for stainless steel pipe dimensions. (For a detailed comparison of manufacturing methods, see our guide: ERW vs Seamless Stainless Steel Pipe.)

Quick Selection Guide:

To select the right stainless steel pipe:

1. Determine Size: Choose the required Nominal Pipe Size (NPS) or DN based on your flow and system design.
2. Select Schedule: Based on your design pressure, select the wall thickness (Schedule). Always specify the "S" series (e.g., Sch 40S) for stainless steel.
3. Verify Standards: Confirm the material meets ASTM A312 requirements and that the tolerances are acceptable for your application.

Stainless Steel Pipe Dimensions – Metric (mm) with Weight (Kg/m)

This table provides the Nominal Bore (mm/inch), Outside Diameter (OD), wall thickness, and weight per meter for common schedules (Sch 5S to XXS) as per ANSI B36.19.

Stainless Steel Pipe OD Chart (Inches with Wall Thickness & Weight per Foot)

This comprehensive schedule chart lists pipe sizes from 8" to 36" NPS, showing OD in inches and wall thickness (inches) / weight per foot (lb/ft) for schedules 5S through DBL E.H. (Double Extra Heavy).

Note: Entries are shown as Wall Thickness (inches) / Weight (lb/ft). Data per ANSI B36.19 and related standards. “-” indicates schedule not available for that size.Note: Entries are shown as Wall Thickness (inches) / Weight (lb/ft). Data per ANSI B36.19 and related standards. “-” indicates schedule not available for that size.

ASME B36.10 vs ASME B36.19 – Core Difference

It is essential to understand that ASME B36.10 covers carbon and alloy steel pipe, while ASME B36.19 covers stainless steel pipe.

For smaller NPS (up to about NPS 8), Sch 40S equals Sch 40 (carbon steel) in wall thickness. However, for NPS 10 and above, Sch 40S is thinner than carbon steel Sch 40.

NPS	Sch 40S (mm)	Sch 40 Carbon (mm)	Difference
10	9.27	12.70	–27%
12	9.53	12.70	–25%
14	9.53	12.70	–25%

This is why you must specify the correct standard when ordering stainless steel pipe.

Common Stainless Steel Pipe Materials (Grades per ASTM A312)

ASTM A312/A312M is the primary material specification for austenitic stainless steel pipe (grades 304, 304L, 316, 316L, 321, 347, etc.) for high-temperature and corrosive service. It references ASME B36.19 for dimensions and also specifies tolerances.

Grade	Type	Key Characteristics
TP304 / 304L	Austenitic	Most common; general corrosive service
TP304H	High-Temp	Modified TP304 for creep resistance
TP316 / 316L	Austenitic	Molybdenum added; better chloride resistance
TP316H	High-Temp	Modified TP316 for creep resistance
TP321 / 321H	Stabilized	Titanium-stabilized; good for welding
TP347 / 347H	Stabilized	Niobium-stabilized; high-temperature strength
TP309H / TP310H	High-Temp	Higher chromium/nickel; extreme heat resistance

Dimension Tolerances per ASTM A312

ASTM A312 covers seamless, welded, and heavily cold worked austenitic stainless steel pipe. The “H” grades (e.g., TP304H, TP316H, TP321H, TP347H) are modified for high-temperature service where creep and stress rupture properties are important.

Dimension	Tolerance	Notes
Outside Diameter (OD)	Varies by size; typically ±0.031″ for 1-1/2″ to 4″ NPS	Tighter tolerances apply for smaller sizes under ASTM A269/A213
Wall Thickness	Seamless: -12.5% under nominal wall thickness	Per ASME SA999
Length	Random lengths normally ordered	Specific tolerances apply per ASTM A530
Out-of-Roundness	Not to exceed specified limits	Varies by NPS

ASTM Specification & Tolerances for Tubing & Piping

This table summarizes allowable outside diameter and wall thickness variations, length tolerances, and required tests for key ASTM standards (A213, A249, A269, A270, A312, A358).

Weight & Thickness of Stainless Steel Gauge Pipes

This table provides the weight per meter for common imperial OD sizes based on standard gauge (SWG) wall thicknesses.

Frequently Asked Questions (FAQ)

1. Is the wall thickness of stainless steel Sch 40S the same as carbon steel Sch 40?

For NPS 8 and smaller, the wall thickness is the same. However, for NPS 10 and above, stainless steel Sch 40S is significantly thinner than carbon steel Sch 40 (e.g., at NPS 10, it's 9.27mm vs. 12.70mm). Always select based on ASME B36.19 for stainless steel.

2. What does the "H" grade mean in ASTM A312 (e.g., TP316H)?

"H" stands for "High Temperature." These grades have slightly higher carbon content and are specifically heat-treated to provide improved creep rupture strength at elevated temperatures, making them suitable for boiler, superheater, and high-temperature service.

3. How do I choose between seamless and welded stainless steel pipes?

For the same NPS and Schedule, the outer diameter and wall thickness are identical. The choice depends on the application:

● Seamless pipes have no longitudinal weld seam, offering better pressure and corrosion resistance for high-pressure, high-temperature, or severe corrosive environments.
● Welded pipes offer tighter dimensional tolerances and are more cost-effective for general industrial and structural uses.

4. What does the tolerance "-12.5% under nominal wall thickness" mean in practice?
This is a standard manufacturing tolerance under ASTM A312. It means that the actual wall thickness at any point on the pipe is permitted to be up to 12.5% thinner than the ordered nominal wall thickness. This must be considered in the design and pressure rating calculations.

5. What are the key testing requirements for stainless steel pipes under ASTM standards?
Key tests include Tension, Flattening, Hardness, and 100% Hydrostatic Testing. For specific applications (e.g., sanitary tubing), additional tests like Reverse Flattening, Flange, or Flare tests may be required. Refer to the detailed table in the "ASTM Specification & Tolerances" section above.

For special specifications, complex applications, or if you need a quote for custom sizes, please contact our technical support team.